Pressure-sensitive labels are typically produced in web form on high-speed narrow web presses wherein the web width typically does not exceed 18 inches. Such machines may be of the offset, rotary letter press, flexographic, or gravure type. Typically, a pressure-sensitive label product is made from a carrier or liner that comprises a continuous web of paper coated with a release agent on the top side and a face paper stock that is coated on its underside with a pressure-sensitive adhesive. These two continuous webs are laminated together with the face stock situated above the liner. The adhesive on the underside of the face paper stock contacts the release coating on the top side of the liner so as to permit the face stock to eventually be separated in the form of labels from the liner without tearing. Prior to separation, the face stock is cut into shapes by rotary dies that do not penetrate through the liner, and the waste face paper stock around the die cut is lifted from the liner to leave a series of successive labels on the liner for further disposition. The labels adhere just enough to the liner to remain attached until being intentionally and automatically separated from the liner.
Rough handling may cause the fragile labels to accidently separate and fall from the liner. This is particularly true when repositionable adhesives are used as the pressure-sensitive adhesive, allowing the labels to be attached, removed and reattached numerous times to a selected surface.
In many instances, newspaper companies are now applying labels to the front page of a newspaper edition for advertising purposes. Such labels are removable from the newspaper by the reader without damaging the newspaper. Typically, the labels are printed on a narrow web press as a web label product, fan-folded into a stack as they issue from the end of the press, and packed into a box that is in turn provided to the newspaper printing establishment. At the newspaper company, the labels are dispensed and applied automatically to the newspapers at speeds sometimes exceeding 1,000 labels per minute.
Fan-folding of webs of pressure sensitive labels is currently accomplished by cross-perforating the web to produce a line of weakness at which the fold can be made. The perforations weaken the liner sufficiently that the web will bend easily at the perforation line and permit fan-folding into the shipping container. However, that same weakened condition creates problems when the labels are to be dispensed at high speeds and applied to the moving newspapers because the perforated liner has a tendency to break at the perforations as a result of the tension and rough handling to which the web is subjected. When a break of the liner occurs as the labels are being applied to newspapers, several thousand newspapers can pass without receiving a label by the time the labeling machine is rethreaded and back in operation. Advertisers have paid for the label to be on the newspapers, but there may be many delivered to customers without the advertisements adhered to the front pages.
Labels are typically supplied to newspaper companies in fan-folded stacks rather than rolls because several fan-folded stacks can be spliced together to provide a continuous supply of labels, whereas if the labels are supplied in roll form, the machine must be stopped when it is time to replace a depleted roll with a new full roll of labels. However, modern fan-folders that produce such stacks typically operate in line with the web presses at speeds approaching 500-1,000 feet per minute, and tension must be kept on the web as it leaves the press and enters the fan-folding machine. Such tension and high speed can combine to cause the cross-perforated webs to break on occasion, and it is always important that the labels be handled as gently as possible to avoid accidentally knocking them loose from the liner.
Typically, adjacent labels on the liner are separated by very narrow gaps or spaces which are many times smaller than the length of the labels themselves. Such gaps are typically no larger than 0.125 inches wide. The cross perforation and subsequent fold line must occur precisely within such spaces without damaging the labels themselves.
The present invention provides a fan-folded web of pressure-sensitive labels wherein the successive fold lines of the product are presented by alternating, oppositely indented creases in the web that are substantially, if not entirely, free of perforations. Such a product substantially eliminates the handling and breakage problems associated with conventional cross-perforated webs of labels both at the production and application ends of the process. In a preferred method and apparatus for making the product, a single rotary die station of a narrow web label press is converted into a creasing station. At such creasing station, the web that carries the pressure-sensitive labels is trained around a stack of die and base rolls in such a manner that alternating, oppositely indented creases or pre-folds are produced in the liner web at predetermined intervals along its length at the gaps between the labels without damaging or loosening the pressure-sensitive labels. Immediately following the crease-forming operations, the web can be introduced into a fan-folding machine which prepares a stack of fan-folded web product for subsequent packaging, the web being slit if necessary longitudinally as it leaves the creasing station and before it enters the fan-folding machine. In a most preferred form of the invention, no perforations at all are present in the pre-fold creases so as to provide maximum strength. However, in some instances a small number of perforations may be acceptable.